The overall objective for our proposed research is to use the emerging field of miRNA research to identify therapeutic targets for acute myeloid leukemia (AML), a genetically and phenotypically heterogeneous disorder of the hematopoietic stem cells that is characterized by failure of blood cells to differentiate and over- production of stem cells. The currently available treatments cure only 1/3rd of the AML patients within the 18-60 year age group. The percentage of relapse deaths observed in complete remission cases is very high. The heterogeneity and diverse patient response and poor survival rate in AML patients warrants the discovery of new molecular therapeutic targets. The recently discovered gene regulatory RNAs known as microRNAs (miRNAs) have been implicated in various types of cancer including lung, breast and chronic lymphocytic leukemia (CLL). miRNAs have also been implicated in early development, cell proliferation and cell death, and cell differentiation. The underlying hypothesis in this project is that specific miRNAs are crucial in the tumorigenesis and disease advancement of leukemia. Specific miRNAs may be able to inhibit crucial genes involved in the growth of leukemia cells in vivo. We propose to use our established miRNA technologies to identify miRNAs that affect AML cell growth and further identify therapeutic targets for AML. We will achieve our long term goal by focusing on the following specific aims: 1) identify functional miRNAs involved in cancer-related cellular functions in AML cell lines. In this study, AML derived cell lines will be transfected with Ambion's pre-miR and anti-miR (miRNA inhibitors) to assess the ability to affect relevant cellular processes including cell proliferation, viability, apoptosis, and telomerase activity; 2) identify targets for miRNA identified in aim 1 above, using bioinformatics prediction of miRNA targets, cDNA microarray expression analysis, and confirmation using Western blot analysis and cell based assays. The combined results of aims 1 and 2 will provide miRNAs of interest that can be explored in aim 3) examine the ability of selected miRNA to kill leukemia cells in a human/murine xenograft model. We will test the activity of specific miRNA to kill primary human leukemia cells and extend animal survival engrafted in a NOD/SCID/B2 mouse model system. Additionally, we will measure the uptake, distribution, and clearance of the miRNA from various fluids and organ compartments using a variety of established hybridization and chromatographic techniques. The combined results from this study may reveal important targets that may be exploited for the development of AML therapeutics. The overall objective for our proposed research is to use the emerging field of miRNA research to identify therapeutic targets for acute myeloid leukemia (AML). miRNAs are an exiting, newly discovered class of regulatory molecules with great potential as therapeutic targets. [unreadable] [unreadable] [unreadable]